A technique producing a contour map of the optic nerve head and quantitative measurements of the optic cup by computer processing of fundus stereophotographs has been developed. Reproducibility of various quantitative factors is significantly better when simultaneous stereophotographs rather than sequential stereophotographs are analyzed. The depth sensitivity of the system ranges from 86 microns to 190 microns depending upon the optics of the fundus camera, the stereoseparation used and the sampling interval employed. Patients with elevated intraocular pressure will be followed in order to evaluate if this method is a more delicate test of early cupping than clinical observation. The possibility of reversing early cupping and field loss by therapy will be explored. The relationship between the quantitative measurements of optic nerve head cupping and visual field loss will be examined.